Everyone has a smoke detector in their house, but few people are prepared for the opposite problem: flooding. If you're worried about springing some leaks during the stormy season, you can alert yourself with a modified smoke alarm.

The whole project should cost you around $15, though if you have an old smoke alarm it'll cost even less. All you need is a large PVC coupler, a sponge, a switch and a wire. You'll need to do a tad bit of soldering, but once you're done, the device is quite simple: just place it on the floor of your basement, and if water starts leaking into the room, the detector will start beeping. Hit the link for more details on the project.